Terephthalic acid esters formation

ABSTRACT

The present disclosure relates to the formation of terephthalate esters. The present invention also relates to the depolymerization of polyethylene terephthalate (PET) or poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) and the recovery of terephthalate esters

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application which claims the benefitof priority from U.S. patent application Ser. No. 15/706,484, filed Sep.15, 2017.

FIELD OF THE INVENTION

The present disclosure relates to the formation of ester derivativesfrom polyesters and more specifically to the formation of terephthalicacid esters from polyethylene terephthalate (PET) or poly(ethyleneglycol-co-1,4-cyclohexanedimethanol terephthalate) (PETG). The presentdisclosure also relates to the formation of dimethyl terephthalate(DMT).

BACKGROUND OF THE INVENTION

The polyethylene terephthalate (PET) bottle resin market has beengrowing strongly as PET resins have replaced glass in carbonated softdrink, bottled water and food containers.

Dimethyl terephthalate (DMT) is primarily used in the manufacture ofpolyethylene terephthalate (PET) for fiber, film, container plastics,and specialty plastics applications.

The largest polyester sector is the fibers market where it is used tomake clothes, home textiles such as sheets and curtains, carpets andrugs, and industrial products such as tire cord, seat belts, hoses andropes. PET film is utilized in electrical applications such asdielectric metal foil capacitors and for food packaging.

The growth in polyester has not been converted into DMT demand. For mostgrades of polyester used in textiles and food and beverage containers,it is more economical to use purified terephthalic acid rather than DMT.

SUMMARY OF THE INVENTION

Disclosed herein is a process for the transformation of a polyesterselected from polyethylene terephthalate and poly(ethyleneglycol-co-1,4-cyclohexanedimethanol terephthalate) into a terephthalateof Formula (I):

-   -   wherein R¹ and R² are independently selected from hydrogen,        C₁-C₆ alkyl, C₁-C₆ haloalkyl, C₁-C₆ hydroxyalkyl, optionally        substituted C₃-C₈ cycloalkyl, optionally substituted (C₁-C₆        alkyl)(C₃-C₈ cycloalkyl), optionally substituted aryl, and        optionally substituted (C₁-C₆ alkyl)(aryl); provided that one of        R¹ or R² is not hydrogen;    -   the process comprising admixing the polyester with a mixture        comprising:        -   (a) a solvent for swelling the polyester;        -   (b) an alcoholic solvent; and        -   (c) a sub-stoichiometric amount of an alkoxide.

In some embodiments, R¹ or R² is methyl.

In some embodiments, the alcoholic solvent is selected from methanol,ethanol, n-propanol, isopropanol, t-butanol, ethylene glycol, glycerol,cyclohexane-1,4-diyldimethanol, phenol, benzyl alcohol, and anycombinations thereof.

In some embodiments, the alcoholic solvent is methanol.

In some embodiments, the solvent for swelling the polyester is selectedfrom a non polar solvent, a polar aprotic solvent, a polar proticsolvent, and any combinations thereof.

In some embodiments, the solvent for swelling the polyester is selectedfrom DMSO, DMF, acetone, a halogenated solvent, n-hexane, nitrobenzene,methanol, benzyl alcohol, benzaldehyde, and any combinations thereof.

In some embodiments, the solvent for swelling the polyester is ahalogenated solvent.

In some embodiments, the ratio of solvent for swelling the polyester toalcoholic solvent is between about 0.1:1 and about 2:1 (w:w).

In some embodiments, the ratio of solvent for swelling the polyester toalcoholic solvent is between about 0.5:1 and about 1:1 (w:w).

In some embodiments, the alkoxide is selected from an alkali metalalkoxide, an alkaline earth metal alkoxide, a metal alkoxide, anammonium alkoxide and any combinations thereof.

In some embodiments, the alkoxide is generated in-situ by addition of analkali metal, an alkaline earth metal, or a metal to the alcoholicsolvent.

In some embodiments, the ratio of polyester to alkoxide is between about15:1 and about 125:1 (w:w).

In some embodiments, the ratio of polyester to alkoxide is between about20:1 and about 25:1 (w:w).

In some embodiments, the admixing of the polyester with the solvent forswelling the polyester, the alkoxide, and the alcoholic solvent isperformed until an about 80% yield of the terephthalate of Formula (I)is achieved.

In some embodiments, the admixing of the polyester with the solvent forswelling the polyester, the alkoxide, and the alcoholic solvent isperformed without external heat.

In some embodiments, the admixing of the polyester with the solvent forswelling the polyester, the alkoxide, and the alcoholic solvent isperformed at atmospheric pressure.

Also disclosed herein is a process for the transformation ofpolyethylene terephthalate into dimethyl terephthalate, comprisingadmixing the polyethylene terephthalate with a mixture comprising:

-   -   (a) a solvent for swelling the polyethylene terephthalate;    -   (b) methanol; and    -   (c) a sub-stoichiometric amount of an alkoxide.

In some embodiments, the solvent for swelling the polyethyleneterephthalate is selected from a halogenated solvent, DMSO, benzylalcohol, methanol, and any combinations thereof.

In some embodiments, the ratio of polyethylene terephthalate to alkoxideis between about 20:1 and about 25:1 (w:w).

In some embodiments, the alkoxide is selected from sodium methoxide,potassium ethoxide, aluminium tri-n-propoxide, and tetrabutylammoniummethoxide.

In some embodiments, the ratio of solvent for swelling the polyester tomethanol is between about 0.5:1 and about 1:1 (w:w).

In some embodiments, the admixing of the polyethylene terephthalate withthe solvent for swelling the polyethylene terephthalate, the alkoxide,and the methanol is performed until an about 80% yield of dimethylterephthalate is achieved.

Also disclosed herein is a reaction mixture comprising:

-   -   (a) a polyester selected from polyethylene terephthalate and        poly(ethylene glycol-co-1,4-cyclohexanedimethanol        terephthalate);    -   (b) a solvent for swelling the polyester;    -   (c) an alcoholic solvent; and    -   (d) a sub-stoichiometric amount of an alkoxide.

In some embodiments, the alcoholic solvent is selected from methanol,ethanol, n-propanol, isopropanol, t-butanol, ethylene glycol, glycerol,cyclohexane-1,4-diyldimethanol, phenol, benzyl alcohol, and anycombinations thereof.

In some embodiments, the solvent for swelling the polyester is selectedfrom a non polar solvent, a polar aprotic solvent, a polar proticsolvent, and any combinations thereof.

In some embodiments, the solvent for swelling the polyester is ahalogenated solvent and the alcoholic solvent is methanol.

In some embodiments, the ratio of solvent for swelling the polyester toalcoholic solvent is between about 0.5:1 and about 1:1 (w:w).

In some embodiments, the ratio of polyester to alkoxide is between about15:1 and about 30:1 (w:w).

In some embodiments, the alkoxide is selected from sodium methoxide,potassium ethoxide, aluminium tri-n-propoxide, and tetrabutylammoniummethoxide.

In some embodiments, the alkoxide is sodium methoxide.

DETAILED DESCRIPTION OF THE INVENTION

Dimethyl terephthalate (DMT) is used in the production of polyesters,including polyethylene terephthalate (PET), polytrimethyleneterephthalate (PTT), and polybutylene terephthalate (PBT). Because DMTis volatile, it is an intermediate in some schemes for the recycling ofPET, e.g. from plastic bottles. Hydrogenation of DMT affords the diol 1,4-cyclohexanedimethanol, which is a useful monomer in the formation ofpolyester resins.

DMT has been produced in a number of ways. Conventionally and still ofcommercial value is the direct esterification of terephthalic acid.Alternatively, it is prepared by alternating oxidation andmethyl-esterification steps from para-xylene via methyl para-toluate.The method for the production of DMT from para-xylene and methanolconsists of four major steps: oxidation, esterification, distillation,and crystallization. A mixture of para-xylene and pare-toluic ester isoxidized with air in the presence of a transition metal catalyst(Co/Mn). The acid mixture resulting from the oxidation is esterifiedwith methanol to produce a mixture of esters. The crude ester mixture isdistilled to remove all the heavy boilers and residue produced; thelighter esters are recycled to the oxidation section. The raw DMT isthen crystallized to remove DMT isomers, residual acids, and aromaticaldehydes.

An Improvement in DMT production from PET recycling: due to the growinguse of PET and PETG in the packaging and fiber (carpet and othertextile) industries there is a need for an efficient, low energy, highyielding, and cost effective way to form DMT from PET or PETG.

Polyesters

Described herein is a process for the transformation of a polyester intoan ester derivative; the process comprising admixing the polyester witha mixture comprising:

-   -   (a) a solvent for swelling the polyester;    -   (b) an alcoholic solvent; and    -   (c) a sub-stoichiometric amount of an alkoxide.

In some embodiments, the polyester is selected from polyethyleneterephthalate (PET), poly(ethylene glycol-co-1,4-cyclohexanedimethanolterephthalate) (PETG), polyglycolide or polyglycolic acid (PGA),polylactic acid (PLA), polycaprolactone (PCL), polyhydroxybutyrate(PHB), polyethylene adipate (PEA), polybutylene succinate (PBS),poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), polybutyleneterephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylenenaphthalate (PEN), Vectran®, cutin, and any combinations thereof.

In some embodiments, the polyester is polyethylene terephthalate (PET):

In some embodiments, the polyester is a terephthalic acid/ethyleneglycol oligomer.

In some embodiments, the polyester is poly(ethyleneglycol-co-1,4-cyclohexanedimethanol terephthalate) (PETG):

In some embodiments, the polyester is polyglycolide or polyglycolic acid(PGA),

In some embodiments, the polyester is polylactic acid (PLA):

In some embodiments, the polyester is polycaprolactone (PCL):

In some embodiments, the polyester is polyhydroxybutyrate (PHB):

In some embodiments, the polyester is polyethylene adipate (PEA):

In some embodiments, the polyester is polybutylene succinate (PBS):

In some embodiments, the polyester ispoly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV):

In some embodiments, the polyester is polybutylene terephthalate (PBT):

In some embodiments, the polyester is polytrimethylene terephthalate(PTT):

In some embodiments, the polyester is polyethylene naphthalate (PEN):

In some embodiments, the polyester is Vectran:

In some embodiments, the polyester is cutin. Cutin is one of two waxypolymers that are the main components of the plant cuticle, which coversall aerial surfaces of plants. Cutin consists of omega hydroxy acids andtheir derivatives, which are interlinked via ester bonds, forming apolyester polymer. There are two major monomer families of cutin, theC16 and C18 families. The C16 family consists mainly of 16-hydroxypalmitic acid and 9,16- or 10,16-dihydroxypalmitic acid. The C18 familyconsists mainly of 18-hydroxy oleic acid, 9,10-epoxy-18-hydroxy stearicacid, and 9,10,18-trihydroxystearate. Tomato cutin consists of16-hydroxy palmitic acid and 10,16-dihydroxypalmitic acid where the10-isomer is largely dominant. The tomato cutin is a polyesterbiopolymer interesterificated. The significant proportion of secondaryesters (esterification in the C-10 secondary hydroxyl) shows that thepolyester structure is significantly branched.

Ester Derivatives

Described herein is a process for the transformation of a polyester intoan ester derivative; the process comprising admixing the polyester witha mixture comprising:

-   -   (a) a solvent for swelling the polyester;    -   (b) an alcoholic solvent; and    -   (c) a sub-stoichiometric amount of an alkoxide.

In some embodiments, the polyester is polyglycolide or polyglycolic acid(PGA) and the ester derivative is a 2-hydroxyacetate derivative. In someembodiments, the ester derivative is methyl 2-hydroxyacetate.

In some embodiments, the polyester is polylactic acid (PLA) and theester derivative is a 2-hydroxypropanoate derivative. In someembodiments, the ester derivative is methyl 2-hydroxypropanoate.

In some embodiments, the polyester is polycaprolactone (PCL) and theester derivative is a 6-hydroxyhexanoate derivative. In someembodiments, the ester derivative is a methyl 6-hydroxyhexanoate.

In some embodiments, the polyester is polyhydroxybutyrate (PHB) and theester derivative is a hydroxybutyrate derivative. In some embodiments,the ester derivative is methyl hydroxybutyrate.

In some embodiments, the polyester is polyethylene adipate (PEA) and theester derivative is an adipate derivative. In some embodiments, theester derivative is dimethyl adipate.

In some embodiments, the polyester is polybutylene succinate (PBS) andthe ester derivative is a succinate derivative. In some embodiments, theester derivative is dimethyl succinate.

In some embodiments, the polyester ispoly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and the esterderivative is a hydroxybutyrate derivative, a hydroxyvaleratederivative, or a combination thereof. In some embodiments, the esterderivative is methyl hydroxybutyrate, methyl hydroxyvalerate, or acombination thereof.

In some embodiments, the polyester is polyethylene naphthalate (PEN) andthe ester derivative is a naphthalate derivative. In some embodiments,the ester derivative is dimethyl naphthalate.

In some embodiments, the polyester is vectran and the ester derivativeis a naphthoate derivative, a benzoate derivative, or a combinationthereof. In some embodiments, the ester derivative is methylhydroxynaphthoate or methyl hydroxybenzoate.

In some embodiments, the polyester is cutin and the ester derivative isa hydroxypalmitate or a dihydroxypalmitate derivative. In someembodiments, the ester derivative is methyl hydroxypalmitate or methyldihydroxypalmitate.

In some embodiments, the polyester is polyethylene terephthalate (PET),poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) (PETG),polytrimethylene terephthalate (PTT), or polybutylene terephthalate(PBT) and the ester derivative is a terephthalate derivative. In someembodiments, the terephthalate derivative is a compound of formula (I):

-   wherein R¹ and R² are independently selected from hydrogen, C₁-C₆    alkyl, C₁-C₆ haloalkyk C₁-C₆ hydroxyalkyl, optionally substituted    C₃-C₈ cycloalkyl, optionally substituted (C₁-C₆ alkyl)(C₃-C₈    cycloalkyl), optionally substituted aryl, and optionally substituted    (C₁-C₆ alkyl)(aryl); provided that one of R¹ or R² is not hydrogen.

In some embodiments of a compound of Formula (I), R¹ and R² areindependently C₁-C₆ alkyl or C₁-C₆ hydroxyalkyl.

In some embodiments of a compound of Formula (I), R¹ and R² areindependently C₁-C₆ alkyl. In some embodiments of a compound of Formula(I), R¹ and R² are independently methyl, ethyl, propyl, isopropyl, orbutyl. In some embodiments of a compound of Formula (I), R¹ and R² areindependently methyl or ethyl. In some embodiments of a compound ofFormula (I), R¹ and R² are methyl. In some embodiments of a compound ofFormula (I), R¹ and R² are ethyl. In some embodiments of a compound ofFormula (I), R¹ and R² are not hydrogen.

In some embodiments of a compound of Formula (I), R¹ and R² areindependently C₁-C₆ hydroxyalkyl. In some embodiments of a compound ofFormula (I), R¹ and R² are independently hydroxyethyl or propanediol. Insome embodiments of a compound of Formula (I), R¹ and R² arehydroxyethyl. In some embodiments of a compound of Formula (I), R¹ andR² are 2-hydroxyethyl. In some embodiments of a compound of Formula (I),R¹ and R² are dihydroxypropyl. In some embodiments of a compound ofFormula (I), R¹ and R² are 2,3-dihydroxypropyl.

In some embodiments of a compound of Formula (I), R¹ and R² areindependently optionally substituted (C₁-C₆ alkyl)(C₃-C₈ cycloalkyl). Insome embodiments of a compound of Formula (I), R¹ and R² areindependently substituted (C₁-C₆ alkyl)(C₃-C₈ cycloalkyl). In someembodiments of a compound of Formula (I), R¹ and R² are4-(hydroxymethyl)cyclohexyl)methyl.

In some embodiments of a compound of Formula (I), R¹ and R² areindependently optionally substituted aryl. In some embodiments of acompound of Formula (I), R¹ and R² are phenyl.

In some embodiments of a compound of Formula (I), R¹ and R² areindependently optionally substituted (C₁-C₆ alkyl)(aryl). In someembodiments of a compound of Formula (I), R¹ and R² are benzyl.

In some embodiments, the ester derivative contains less than about 10%impurity (w/w). In some embodiments, the ester derivative contains lessthan about 9% impurity (w/w). In some embodiments, the ester derivativecontains less than about 8% impurity (w/w). In some embodiments, theester derivative contains less than about 7% impurity (w/w). In someembodiments, the ester derivative contains less than about 6% impurity(w/w). In some embodiments, the ester derivative contains less thanabout 5% impurity (w/w). In some embodiments, the ester derivativecontains less than about 4% impurity (w/w). In some embodiments, theester derivative contains less than about 3% impurity (w/w). In someembodiments, the ester derivative contains less than about 2% impurity(w/w). In some embodiments, the ester derivative contains less thanabout 1% impurity (w/w). In some embodiments, the ester derivativecontains less than about 0.5% impurity (w/w). In some embodiments, theester derivative contains less than about 0.4% impurity (w/w). In someembodiments, the ester derivative contains less than about 0.3% impurity(w/w). In some embodiments, the ester derivative contains less thanabout 0.2% impurity (w/w). In some embodiments, the ester derivativecontains less than about 0.1% impurity (w/w).

In some embodiments, the ester derivative contains less than about 250ppm of any metals, less than about 240 ppm of any metals, less thanabout 230 ppm of any metals, less than about 220 ppm of any metals, lessthan about 210 ppm of any metals, less than about 200 ppm of any metals,less than about 190 ppm of any metals, less than about 180 ppm of anymetals, less than about 170 ppm of any metals, less than about 160 ppmof any metals, less than about 150 ppm of any metals, less than about140 ppm of any metals, less than about 130 ppm of any metals, less thanabout 120 ppm of any metals, less than about 110 ppm of any metals, lessthan about 100 ppm of any metals, less than about 90 ppm of any metals,less than about 80 ppm of any metals, less than about 70 ppm of anymetals, less than about 60 ppm of any metals, less than about 50 ppm ofany metals, less than about 40 ppm of any metals, less than about 30 ppmof any metals, less than about 20 ppm of any metals, less than about 10ppm of any metals, less than about 5 ppm of any metals, less than about4 ppm of any metals, less than about 3 ppm of any metals, less thanabout 2 ppm of any metals, less than about 1 ppm of any metals, lessthan about 0.9 ppm of any metals, less than about 0.8 ppm of any metals,less than about 0.7 ppm of any metals, less than about 0.6 ppm of anymetals, less than about 0.5 ppm of any metals, less than about 0.4 ppmof any metals, less than about 0.3 ppm of any metals, less than about0.2 ppm of any metals, less than about 0.1 ppm of any metals, less thanabout 0.09 ppm of any metals, less than about 0.08 ppm of any metals,less than about 0.07 ppm of any metals, less than about 0.06 ppm of anymetals, less than about 0.05 ppm of any metals, less than about 0.04 ppmof any metals, less than about 0.03 ppm of any metals, less than about0.02 ppm of any metals, or less than about 0.01 ppm of any metals.

Alcoholic Solvent

Described herein is a process for the transformation of a polyester intoan ester derivative; the process comprising admixing the polyester witha mixture comprising:

-   -   (a) a solvent for swelling the polyester;    -   (b) an alcoholic solvent; and    -   (c) a sub-stoichiometric amount of an alkoxide.

In some embodiments, the process described herein comprises an alcoholicsolvent. In some embodiments, the alcoholic solvent is a linear alcohol,branched alcohol, cyclic alcohol, or any combinations thereof. In someembodiments, the alcoholic solvent is selected from methanol, ethanol,n-propanol, isopropanol, t-butanol, ethylene glycol, glycerol,cyclohexane-1,4-diyldimethanol, phenol, benzyl alcohol, and anycombinations thereof.

In some embodiments, the alcoholic solvent is a linear C₁-C₄ alcohol. Insome embodiments, the alcoholic solvent is methanol, ethanol, propanol,butanol, or a combination thereof. In some embodiments, the alcoholicsolvent is methanol, ethanol, propanol, or a combination thereof. Insome embodiments, the alcoholic solvent is methanol. In someembodiments, the alcohol is ethanol. In some embodiments, the alcoholicsolvent is a branched C₃-C₄ alcohol. In some embodiments, the alcoholicsolvent is t-butanol, s-butanol, i-butanol, propanol, or anycombinations thereof. In some embodiments, the alcoholic solvent is acyclic C₃-C₈ alcohol. In some embodiments, the alcoholic solvent iscyclopropanol, cyclobutanol, cyclopentanol, cyclohexanol, cycloheptanol,cyclohexane-1,4-diyldimethanol, or any combinations thereof. In someembodiments, the alcoholic solvent is cyclohexane-1,4-diyldimethanol.

In some embodiments, the alcoholic solvent is a polyol. In someembodiments, the alcoholic solvent is selected from ethylene glycol,glycerol, and any combinations thereof.

In some embodiments, the alcoholic solvent is selected from phenol,benzyl alcohol, and any combinations thereof.

Solvent for Swelling the Polyester

Described herein is a process for the transformation of a polyester intoan ester derivative; the process comprising admixing the polyester witha mixture comprising:

-   -   (a) a solvent for swelling the polyester;    -   (b) an alcoholic solvent; and    -   (c) a sub-stoichiometric amount of an alkoxide.

In some embodiments, the process described herein comprises pre-treatingthe polyester with a solvent for swelling the polyester prior to theaddition of the alcoholic solvent and alkoxide. In some embodiments, thepre-treatment with the solvent for swelling the polyester is done forbetween about 5 mins and about 60 mins prior to the addition of thealcoholic solvent and alkoxide. In some embodiments, the pre-treatmentwith the solvent for swelling the polyester is done for between about 5mins and about 40 mins prior to the addition of the alcoholic solventand alkoxide. In some embodiments, the pre-treatment with the solventfor swelling the polyester is done for between about 5 mins and about 20mins prior to the addition of the alcoholic solvent and alkoxide. Insome embodiments, the pre-treatment with the solvent for swelling thepolyester is done for between about 5 mins and about 10 mins prior tothe addition of the alcoholic solvent and alkoxide. In some embodiments,the pre-treatment with the solvent for swelling the polyester is donefor about 5 mins. In some embodiments, the pre-treatment with thesolvent for swelling the polyester is done for about 10 mins. In someembodiments, the pre-treatment with the solvent for swelling thepolyester is done for about 15 mins. In some embodiments, thepre-treatment with the solvent for swelling the polyester is done forabout 20 mins. In some embodiments, the pre-treatment with the solventfor swelling the polyester is done for about 25 mins. In someembodiments, the pre-treatment with the solvent for swelling thepolyester is done for about 30 mins. In some embodiments, thepre-treatment with the solvent for swelling the polyester is done forabout 35 mins. In some embodiments, the pre-treatment with the solventfor swelling the polyester is done for about 40 mins. In someembodiments, the pre-treatment with the solvent for swelling thepolyester is done for about 45 mins. In some embodiments, thepre-treatment with the solvent for swelling the polyester is done forabout 50 mins. In some embodiments, the pre-treatment with the solventfor swelling the polyester is done for about 55 mins. In someembodiments, the pre-treatment with the solvent for swelling thepolyester is done for about 60 mins.

In some embodiments, the process described herein comprises treating thepolyester with a solvent for swelling the polyester at the same time asthe addition of the alcoholic solvent and alkoxide.

In some embodiments, the solvent for swelling the polyester is selectedfrom a non polar solvent, a polar aprotic solvent, a polar proticsolvent, and any combinations thereof.

In some embodiments, the solvent for swelling the polyester is selectedfrom dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), acetone, ahalogenated solvent, n-hexane, nitrobenzene, methanol, benzyl alcohol,benzaldehyde, and any combinations thereof. In some embodiments, thesolvent for swelling the polyester is selected from DMSO, a halogenatedsolvent, and any combinations thereof. In some embodiments, the solventfor swelling the polyester is DMSO. In some embodiments, the solvent forswelling the polyester is a halogenated solvent. In some embodiments,the solvent for swelling the polyester is a chlorinated solvent. In someembodiments, the solvent for swelling the polyester is dichloromethane,dichloroethane, tetrachloroethane, chloroform, tetrachloromethane,trichloroethane, or any combinations thereof. In some embodiments, thesolvent for swelling the polyester is dichloromethane. In someembodiments, the solvent for swelling the polyester is methanol.

In some embodiments, the ratio of solvent for swelling the polyester toalcoholic solvent is between about 0.1:1 and about 2:1 (w:w). In someembodiments, the ratio of solvent for swelling the polyester toalcoholic solvent is between about 1:1 and about 2:1 (w:w). In someembodiments, the ratio of solvent for swelling the polyester toalcoholic solvent is between about 0.1:1 and about 2:1 (w:w), or betweenabout 0.2:1 and about 2:1 (w:w), or between about 0.3:1 and about 2:1(w:w), or between about 0.4:1 and about 2:1 (w:w), or between about0.5:1 and about 2:1 (w:w), or between about 0.6:1 and about 2:1 (w:w),or between about 0.7:1 and about 2:1 (w:w), or between about 0.8:1 andabout 2:1 (w:w), or between about 0.9:1 and about 2:1 (w:w), or betweenabout 1:1 and about 2:1 (w:w), or between about 1:2 and about 2:1 (w:w),or between about 1:3 and about 2:1 (w:w), or between about 1:4 and about2:1 (w:w), or between about 1:4 and about 2:1 (w:w), or between about1:6 and about 2:1 (w:w), or between about 1:7 and about 2:1 (w:w), orbetween about 1:8 and about 2:1 (w:w), or between about 1:9 and about2:1 (w:w), or between about 0.5:1 and about 1.5:1 (w:w), or betweenabout 0.8:1 and about 1.2:1 (w:w), or between about 0.5:1 and about 1:1(w:w), or between about 1:1 and about 1.5:1 (w:w). In some embodiments,the ratio of solvent for swelling the polyester to alcoholic solvent isbetween about 0.5:1 and about 1:1 (w:w).

Alkoxides

Described herein is a process for the transformation of a polyester intoan ester derivative; the process comprising admixing the polyester witha mixture comprising:

-   -   (a) a solvent for swelling the polyester;    -   (b) an alcoholic solvent; and    -   (c) a sub-stoichiometric amount of an alkoxide.

In some embodiments, the process described herein comprises adding asub-stoichiometric amount of an alkoxide. In some embodiments, theprocess described herein comprises adding a catalytic amount of analkoxide.

“Sub-stoichiometric amount”, as used herein, is used to indicate thatthe amount of material used is less than a stoichiometric amount. Theterm is used herein interchangeably with “catalytic amount.” In someembodiments, a sub-stoichiometric amount is less than or equal to about95% of a stoichiometric amount. In some embodiments, asub-stoichiometric amount is less than or equal to about 90% of astoichiometric amount. In some embodiments, a sub-stoichiometric amountis less than or equal to about 85% of a stoichiometric amount. In someembodiments, a sub-stoichiometric amount is less than or equal to about80% of a stoichiometric amount. In some embodiments, asub-stoichiometric amount is less than or equal to about 75% of astoichiometric amount. In some embodiments, a sub-stoichiometric amountis less than or equal to about 70% of a stoichiometric amount. In someembodiments, a sub-stoichiometric amount is less than or equal to about65% of a stoichiometric amount. In some embodiments, asub-stoichiometric amount is less than or equal to about 60% of astoichiometric amount. In some embodiments, a sub-stoichiometric amountis less than or equal to about 55% of a stoichiometric amount. In someembodiments, a sub-stoichiometric amount is less than or equal to about50% of a stoichiometric amount. In some embodiments, asub-stoichiometric amount is less than or equal to about 45% of astoichiometric amount. In some embodiments, a sub-stoichiometric amountis less than or equal to about 40% of a stoichiometric amount. In someembodiments, a sub-stoichiometric amount is less than or equal to about35% of a stoichiometric amount. In some embodiments, asub-stoichiometric amount is less than or equal to about 30% of astoichiometric amount. In some embodiments, a sub-stoichiometric amountis less than or equal to about 25% of a stoichiometric amount. In someembodiments, a sub-stoichiometric amount is less than or equal to about20% of a stoichiometric amount. In some embodiments, asub-stoichiometric amount is less than or equal to about 15% of astoichiometric amount. In some embodiments, a sub-stoichiometric amountis less than or equal to about 10% of a stoichiometric amount.

“Stoichiometric amount”, as used herein, is used to indicate that theamount of material used is equivalent to the number of ester linkagespresent in the polyester.

In some embodiments, the alkoxide, which comprises an alkoxide anion anda cation is selected from an alkali metal alkoxide, an alkaline earthmetal alkoxide, a metal alkoxide, an ammonium alkoxide, and anycombinations thereof. In some embodiments, the alkoxide anion is a C₁-C₄alkoxide anion. In some embodiments, the alkoxide anion is selected frommethoxide, ethoxide, n-propoxide, n-butoxide, t-butoxide, sec-butoxide,iso-butoxide, iso-propoxide, and a combination thereof. In someembodiments, the alkoxide anion is methoxide, ethoxide, or anycombinations thereof. In some embodiments, the alkoxide anion ismethoxide. In some embodiments, the cation is lithium, sodium,potassium, magnesium, calcium, strontium, barium, zinc, aluminum, orammonium. In some embodiments, the alkoxide is sodium methoxide,potassium ethoxide, or aluminium tri-n-propoxide. In some embodiments,the ammonium alkoxide is a tetraalkylammonium alkoxide. In someembodiments, the ammonium alkoxide is a tetrabutylammonium alkoxide. Insome embodiments, the alkoxide is sodium methoxide, potassium ethoxide,aluminium tri-n-propoxide, or tetrabutylammonium methoxide.

In some embodiments, the alkoxide is generated in-situ by addition of analkali metal, an alkaline earth metal, or a metal to the alcoholicsolvent.

In some embodiments, the ratio of polyester to alkoxide is between about15:1 and about 125:1 (w:w), or between about 15:1 and about 100:1 (w:w),or between about 15:1 and about 80:1 (w:w), or between about 15:1 andabout 60:1 (w:w), or between about 15:1 and about 40:1 (w:w), or betweenabout 15:1 and about 25:1 (w:w), or between about 15:1 and about 20:1(w:w), or between about 20:1 and about 25:1 (w:w), or between about 20:1and about 50:1 (w:w), or between about 30:1 and about 60:1 (w:w), orbetween about 40:1 and about 70:1 (w:w), or between about 50:1 and about80:1 (w:w), or between about 60:1 and about 90:1 (w:w), or between about20:1 and about 125:1 (w:w), or between about 40:1 and about 125:1 (w:w),or between about 60:1 and about 125:1 (w:w), or between about 80:1 andabout 125:1 (w:w), or between about 100:1 and about 125:1 (w:w). In someembodiments, the ratio of polyester to alkoxide is between about 20:1and about 25:1 (w:w).

Reaction Time

Described herein is a process for the transformation of a polyester intoan ester derivative; the process comprising admixing the polyester witha mixture comprising:

-   -   (a) a solvent for swelling the polyester;    -   (b) an alcoholic solvent; and    -   (c) a sub-stoichiometric amount of an alkoxide.

In some embodiments, the admixing of the polyester with the solvent forswelling the polyester, the alkoxide, and the alcoholic solvent isperformed for a sufficient time. In some embodiments, the admixing ofthe polyester with the solvent for swelling the polyester, the alkoxide,and the alcoholic solvent is performed until an about 70% yield ofdesired ester is achieved. In some embodiments, the admixing of thepolyester with the solvent for swelling the polyester, the alkoxide, andthe alcoholic solvent is performed until an about 75% yield of desiredester is achieved. In some embodiments, the admixing of the polyesterwith the solvent for swelling the polyester, the alkoxide, and thealcoholic solvent is performed until an about 80% yield of desired esteris achieved. In some embodiments, the admixing of the polyester with thesolvent for swelling the polyester, the alkoxide, and the alcoholicsolvent is performed until an about 85% yield of desired ester isachieved. In some embodiments, the admixing of the polyester with thesolvent for swelling the polyester, the alkoxide, and the alcoholicsolvent is performed until an about 90% yield of desired ester isachieved. In some embodiments, the admixing of the polyester with thesolvent for swelling the polyester, the alkoxide, and the alcoholicsolvent is performed until an about 95% yield of desired ester isachieved.

In some embodiments, the admixing of the polyester with the solvent forswelling the polyester, the alkoxide, and the alcoholic solvent isperformed for between about 10 mins and 5 hrs, or between about 10 minsand 4 hrs, or between about 10 mins and 3 hrs, or between about 10 minsand 2 hrs, or between about 20 mins and 2 hrs, or between about 30 minsand 2 hrs, or between about 40 mins and 2 hrs, or between about 30 minsand 1 hr, or between about 30 mins and 1.5 hrs. In some embodiments, theadmixing of the polyester with the solvent for swelling the polyester,the alkoxide, and the alcoholic solvent is performed for about 10 mins,or about 15 mins, or about 20 mins, or about 25 mins, or about 30 mins,or about 35 mins, or about 40 mins, or about 45 mins, or about 50 mins,or about 60 mins, or about 70 mins, or about 80 mins, or about 90 mins,or about 100 mins, or about 110 mins, or about 120 mins, or about 130mins, or about 140 mins, or about 150 mins, or about 160 mins, or about170 min, or about 180 mins. In some embodiments, the admixing of thepolyester with the solvent for swelling the polyester, the alkoxide, andthe alcoholic solvent is performed for about 1 hr, or about 2 hrs, orabout 3 hrs, about 4 hrs, or about 5 hrs.

Temperature

Described herein is a process for the transformation of a polyester intoan ester derivative; the process comprising admixing the polyester witha mixture comprising:

-   -   (a) a solvent for swelling the polyester;    -   (b) an alcoholic solvent; and    -   (c) a sub-stoichiometric amount of an alkoxide.

In some embodiments, the process disclosed herein is conducted atambient temperature. In some embodiments, ambient temperature is 25±5°C.

In some embodiments, the process disclosed herein is conducted withoutexternal heat. In some embodiments, the process is exothermic and thetemperature of the reaction mixture rises to at least 30° C., at least35° C., at least 40° C., at least 45° C., at least 50° C., at least 55°C., or at least 60° C. In some embodiments, no external heat sources areused to increase the temperature of the reaction mixture.

In some embodiments, the process disclosed herein is conducted withexternal heat. In some embodiments, the process disclosed herein isconducted with external heat at between about 25° C. and about 80° C.,or between about 25° C. and about 60° C., or between about 40° C. andabout 60° C., or between about 40° C. and about 50° C., or between about30° C. and about 50° C. In some embodiments, the process disclosedherein is conducted at about 26° C., about 27° C., about 28° C., about29° C., about 30° C., about 31° C., about 32° C., about 33° C., about34° C., about 35° C., about 36° C., about 37° C., about 38° C., about39° C., about 40° C., about 41° C., about 42° C., about 43° C., about44° C., about 45° C., about 46° C., about 47° C., about 48° C., about49° C., about 50° C., about 51° C., about 52° C., about 53° C., about54° C., about 55° C., about 56° C., about 57° C., about 58° C., about59° C., about 60° C., about 65° C., about 70° C., about 75° C., or about80° C.

Pressure

In some embodiments, the process disclosed herein is conducted atatmospheric pressure. In some embodiments, the process disclosed hereinis conducted at elevated pressures. In some embodiments, the processdisclosed herein is conducted at a pressure between about atmosphericpressure and about 220 psi, or between about atmospheric pressure andabout 200 psi, or between about atmospheric pressure and about 150 psi,or between about atmospheric pressure and about 100 psi, or betweenabout atmospheric pressure and about 50 psi, or between about 20 andabout 150 psi, or between about 50 and about 100 psi. In someembodiments, the process disclosed herein is conducted at about 14 psi,about 15 psi, about 16 psi, about 17 psi, about 18 psi, about 19 psi,about 20 psi, about 30 psi, about 40 psi, about 50 psi, about 60 psi,about 70 psi, about 80 psi, about 90 psi, about 100 psi, about 110 psi,about 120 psi, about 130 psi, about 140 psi, about 150 psi, about 160psi, about 170 psi, about 180 psi, about 190 psi, about 200 psi, about210 psi, or about 220 psi.

Agitation

Described herein is a process for the transformation of a polyester intoan ester derivative; the process comprising admixing the polyester witha mixture comprising:

-   -   (a) a solvent for swelling the polyester;    -   (b) an alcoholic solvent; and    -   (c) a sub-stoichiometric amount of an alkoxide.

In some embodiments, the process disclosed herein is conducted withoutagitation. In some embodiments, the process disclosed herein isconducted with increased agitation. In some embodiments, a stirred batchreactor is used to provide agitation. In some embodiments, a continuousreactor is used to provide agitation.

Certain Terminology

The section headings used herein are for organizational purposes onlyand are not to be construed as limiting the subject matter described.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as is commonly understood to which the claimedsubject matter belongs. In the event that there are a plurality ofdefinitions for terms herein, those in this section prevail.

It is to be understood that the general description and the detaileddescription are exemplary and explanatory only and are not restrictiveof any subject matter claimed. In this application, the use of thesingular includes the plural unless specifically stated otherwise. Itmust be noted that, as used in the specification and the appendedclaims, the singular forms “a,” “an” and “the” include plural referentsunless the context clearly dictates otherwise. In this application, theuse of “or” means “and/or” unless stated otherwise. Furthermore, use ofthe term “including” as well as other forms, such as “include”,“includes,” and “included,” is not limiting.

Unless the context requires otherwise, throughout the specification andclaims which follow, the word “comprise” and variations thereof, suchas, “comprises” and “comprising” are to be construed in an open,inclusive sense, that is, as “including, but not limited to.” Further,headings provided herein are for convenience only and do not interpretthe scope or meaning of the claimed invention.

As used in this specification and the appended claims, the singularforms “a,” “an,” and “the” include plural referents unless the contentclearly dictates otherwise. It should also be noted that the term “or”is generally employed in its sense including “and/or” unless the contentclearly dictates otherwise.

As used herein, the term “about” or “approximately” means within 10%,preferably within 10%, and more preferably within 5% of a given value orrange.

As used herein, ambient temperature is a colloquial expression for thetypical or preferred indoor (climate-controlled) temperature to whichpeople are generally accustomed. It represents the small range oftemperatures at which the air feels neither hot nor cold, approximately21° C. In some embodiments, ambient temperature is 25±5° C. In someembodiments, ambient temperature is 18° C. In some embodiments, ambienttemperature is 19° C. In some embodiments, ambient temperature is 20° C.In some embodiments, ambient temperature is 21° C. In some embodiments,ambient temperature is 22° C. In some embodiments, ambient temperatureis 23° C. In some embodiments, ambient temperature is 24° C. In someembodiments, ambient temperature is 25° C. In some embodiments, ambienttemperature is 26° C. In some embodiments, ambient temperature is 27° C.In some embodiments, ambient temperature is 28° C. In some embodiments,ambient temperature is 29° C. In some embodiments, ambient temperatureis 30° C.

As used in this specification and the appended claims, depolymerization,refer to a way of breaking down a polymer to its starting material. Itis essentially the opposite of polymerization. In some embodiments, thedepolymerization is achieved by glycolysis, methanolysis or hydrolysis,categorized by the depolymerization reactant used, such as glycol,methanol or water, respectively.

Definition of standard chemistry terms may be found in reference works,including but not limited to, Carey and Sundberg “Advanced OrganicChemistry 4^(th) Ed.” Vols. A (2000) and B (2001), Plenum Press, NewYork.

The terms below, as used herein, have the following meanings, unlessindicated otherwise:

“Alkyl” refers to a straight or branched hydrocarbon chain radical whichis attached to the rest of the molecule by a single bond. A linear alkylcomprising up to 4 carbon atoms is referred to as a linear C₁-C₄ alkyl,likewise, for example, a linear alkyl comprising up to 3 carbon atoms isa linear C₁-C₃ alkyl. Linear alkyl groups include linear C₁-C₄ alkyl,linear C₁-C₃ alkyl, linear C₁-C₂ alkyl, linear C₂-C₃ alkyl and linearC₂-C₄ alkyl. Representative alkyl groups include, methyl, ethyl, propyl,and butyl. A branched alkyl comprising between 3 and 4 carbon atoms isreferred to as a branched C₃-C₄ alkyl. Representative branched alkylgroups include, but are not limited to t-butyl, sec-butyl, isobutyl, andisopropyl. Unless stated otherwise specifically in the specification, analkyl is optionally substituted with oxo, halogen, —CN, —CF₃, —OH, —OMe,—NH₂, or —NO₂. In some embodiments, an alkyl is optionally substitutedwith oxo, halogen, —CN, —CF₃, —OH, or —OMe. In some embodiments, thealkyl is optionally substituted with halogen.

“Halo” or “halogen” refers to bromo, chloro, fluoro or iodo. In someembodiments, halogen is fluoro or chloro. In some embodiments, halogenis fluoro.

“Haloalkyl” refers to an alkyl radical, as defined above, that issubstituted by one or more halo atoms, as defined above, e.g.,trifluoromethyl, difluoromethyl, fluoromethyl, trichloromethyl,2,2,2-trifluoroethyl, 1,2-difluoroethyl, 3-bromo-2-fluoropropyl,1,2-dibromoethyl, and the like.

“Hydroxyalkyl” refers to an alkyl radical, as defined above, that issubstituted by one or more —OH groups, e.g., hydroxymethyl,hydroxyethyl, hydroxypropyl, propanediol, and the like.

“Cycloalkyl” refers to a stable, partially or fully saturated,monocyclic or polycyclic carbocyclic ring, which may include fused orbridged ring systems. Representative cycloalkyls include, but are notlimited to, cycloalkyls having from three to fifteen carbon atoms(C₃-C₁₅ cycloalkyl), from three to ten carbon atoms (C₃-C₁₀ cycloalkyl),from three to eight carbon atoms (C₃-C₈ cycloalkyl), from three to sixcarbon atoms (C₃-C₆ cycloalkyl), from three to five carbon atoms (C₃-C₅cycloalkyl), or three to four carbon atoms (C₃-C₄ cycloalkyl). In someembodiments, the cycloalkyl is a 3- to 6-membered cycloalkyl. In someembodiments, the cycloalkyl is a 5- to 6-membered cycloalkyl. Monocycliccycloalkyls include, for example, cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, cycloheptyl, and cyclooctyl. Polycyclic cycloalkyls orcarbocycles include, for example, adamantyl, norbornyl, decalinyl,bicyclo[3.3.0]octane, bicyclo[4.3.0]nonane, cis-decalin, trans-decalin,bicyclo[2.1.1]hexane, bicyclo[2.2.1]heptane, bicyclo[2.2.2]octane,bicyclo[3.2.2]nonane, and bicyclo[3.3.2]decane, and7,7-dimethyl-bicyclo[2.2.1]heptanyl. Partially saturated cycloalkylsinclude, for example cyclopentenyl, cyclohexenyl, cycloheptenyl, andcyclooctenyl. Unless stated otherwise specifically in the specification,a cycloalkyl is optionally substituted with oxo, halogen, methyl, ethyl,—CN, —CF₃, —OH, —OMe, —NH₂, or —NO₂. In some embodiments, a cycloalkylis optionally substituted with oxo, halogen, methyl, ethyl, —CN, —CF₃,—OH, or —OMe. In some embodiments, the cycloalkyl is optionallysubstituted with halogen.

“Aryl” refers to a radical derived from a hydrocarbon ring systemcomprising hydrogen, 6 to 30 carbon atoms and at least one aromaticring. The aryl radical may be a monocyclic, bicyclic, tricyclic ortetracyclic ring system, which may include fused or bridged ringsystems. In some embodiments, the aryl is a 6- to 10-membered aryl. Insome embodiments, the aryl is a 6-membered aryl. Aryl radicals include,but are not limited to, aryl radicals derived from the hydrocarbon ringsystems of anthrylene, naphthylene, phenanthrylene, anthracene, azulene,benzene, chrysene, fluoranthene, fluorene, as-indacene, s-indacene,indane, indene, naphthalene, phenalene, phenanthrene, pleiadene, pyrene,and triphenylene. In some embodiments, the aryl is phenyl. Unless statedotherwise specifically in the specification, an aryl may be optionallysubstituted, for example, with halogen, amino, nitrile, nitro, hydroxyl,alkyl, alkenyl, alkynyl, haloalkyl, alkoxy, aryl, cycloalkyl,heterocycloalkyl, heteroaryl, and the like. In some embodiments, an arylis optionally substituted with halogen, methyl, ethyl, —CN, —CF₃, —OH,—OMe, —NH₂, or —NO₂. In some embodiments, an aryl is optionallysubstituted with halogen, methyl, ethyl, —CN, —CF₃, —OH, or —OMe. Insome embodiments, the aryl is optionally substituted with halogen.

EXAMPLES

The following examples are intended to illustrate but not limit thedisclosed embodiments.

Example 1

Polyethylene terephthalate (1000 g) was introduced in a reactor.Dichloromethane (500 g) was added and the mixture was stirred at roomtemperature and at atmospheric pressure for about 40 mins. Sodiummethoxide and methanol were then added to the reaction mixture wasstirred and heated for 120 mins (see table below for amounts, time, andtemperature details).

The reaction mixture was then filtered and the filter cake was washedwith methanol. The filter cake was then melted and filtered at 140° C.to remove any unreacted materials. The filtered dimethyl terephthalatewas then distilled under vacuum at 200° C. The liquid recovered from thefiltration was distilled to recover the solvents and the mono ethyleneglycol.

Weight of Weight of sodium Reaction Reaction methanol methoxide timetemperature Yield (g) (g) (min) (° C.) (%) Example 1A 667 32 120 55 90Example 1B 600 54 120 50 90 Example 1C 580 50 120 60 90

Example 2

Polyethylene terephthalate (1000 g) was introduced in a reactor. DMSO(500 g) was added and the mixture was stirred at room temperature and atatmospheric pressure for about 40 mins. Sodium methoxide (45 g) andmethanol (550 g) were then added to the reaction mixture was stirred andheated at 55° C. for 120 mins.

The reaction mixture was then filtered and the filter cake was washedwith methanol. The filter cake was then melted and filtered at 140° C.to remove any unreacted materials. The filtered dimethyl terephthalatewas then distilled under vacuum at 200° C. The liquid recovered from thefiltration was distilled to recover the solvents and the mono ethyleneglycol.

Dimethyl terephthalate was obtained in 89% yield.

1.-30. (canceled)
 31. A process for the transformation of a polyesterselected from polyethylene terephthalate and poly(ethyleneglycol-co-1,4-cyclohexanedimethanol terephthalate) into dimethylterephthalate; the process comprising admixing the polyester with amixture comprising: (a) methanol; (b) a sub-stoichiometric amount of analkoxide; wherein the process is performed at a temperature betweenabout 25° C. and about 80° C.; wherein the ratio of the polyester to thealkoxide is between about 20:1 and about 50:1 (w:w); and wherein theprocess achieves at least about 70% yield of dimethyl terephthalate. 32.The process of claim 1, wherein the alkoxide is selected from an alkalimetal alkoxide, an alkaline earth metal alkoxide, a metal alkoxide, anammonium alkoxide and any combinations thereof.
 33. The process of claim1, wherein the alkoxide is selected from sodium methoxide, potassiumethoxide, aluminium tri-n-propoxide, and tetrabutylammonium methoxide.34. The process of claim 1, wherein the alkoxide is sodium methoxide.35. The process of claim 1, wherein the alkoxide is generated in-situ byaddition of an alkali metal, an alkaline earth metal, or a metal to themethanol.
 36. The process of claim 1, wherein the ratio of the polyesterto the alkoxide is between about 20:1 and about 25:1 (w:w).
 37. Theprocess of claim 1, wherein the process achieves at least about 80%yield of dimethyl terephthalate.
 38. The process of claim 1, wherein theprocess achieves at least about 90% yield of dimethyl terephthalate. 39.The process of claim 1, wherein the process achieves at least about 95%yield of dimethyl terephthalate.
 40. The process of claim 1, wherein theprocess is performed at atmospheric pressure.